1. Field
The subject matter disclosed herein relates to electronic devices, and more particularly to methods, apparatuses and articles of manufacture for adaptive passive scanning and/or adaptive active probing techniques to support mobile device positioning.
2. Information
Mobile devices, such as mobile phones, notebook, computers, etc., typically have the ability to estimate location and/or position with a high degree of precision using any one of several technologies such as, for example, satellite positioning systems (e.g., GPS and the like), advanced forward-link trilateration (AFLT), just to name a few examples of signal-based positioning systems and/or corresponding signal-based positioning signals. Using high precision location information, applications for a mobile device may provide a user with various services, such as, for example, vehicle/pedestrian navigation, location-based searching, just to name a couple of examples. Here, high precision signal-based location information (e.g., obtained from GPS and/or other signal-based positioning systems) may be processed according to a global coordinate system (e.g., latitude and longitude or earth-centered xyz coordinates). While such use of signal-based location information referenced to a global coordinate system may be useful in providing some services (e.g., outdoor vehicle navigation), such signal-based location information referenced to a global coordinate system may be impractical for other types of services such as indoor pedestrian navigation.
In certain indoor environments, such as office buildings, shopping malls, airports, stadiums, etc., certain example signal-based positioning techniques may make use of various terrestrial-based wireless signal transmitting devices, e.g., wireless network service access transceivers, cellular network base stations, special-purpose beacon transmitters, etc., that transmit wireless signals which may be acquired by the mobile device and used for positioning purposes. For example, a mobile device may receive a signal-based positioning signal from a transmitter and based thereon determine a pseudorange between the transmitter and receiver. Hence, for example, positioning may be provided based on trilateration and/or other known signal-based positioning techniques.
In some implementations, an indoor navigation system may provide a digital electronic map to mobile devices as they enter a particular indoor area. Such an electronic map may show indoor features such as doors, hallways, entry ways, walls, etc., points of interest such as bathrooms, pay phones, room names, stores, etc. Such an electronic map may be stored at a server to be accessible by a mobile device through selection of a URL, for example. By obtaining and rendering all or part of an electronic map via a display mechanism, a mobile device may, for example, overlay a current location of the mobile device (and user) over the displayed map to provide the user with additional context.
In certain instances, in addition to an electronic map, an indoor navigation system may selectively provide assistance information to mobile devices to facilitate and/or enable various location based services. Such assistance information may include, for example, information to facilitate measurements of ranges to wireless service access transceivers at known fixed locations. In one implementation, For example, a “radio heatmap” or “probability heatmap” indicating and/or otherwise modeling expected RSSI and/or round-trip delay times at particular locations associated with service access transceivers may enable a mobile device to associate acquired signal measurements with one of the particular locations in an indoor environment. Here, for example, grid points may be laid over locations in an indoor environment at a uniform spacing (e.g., 0.5 meter separation of neighboring grid points), or possibly with non-uniform spacing. Thus, radio heatmap and/or other corresponding probability functions/models may be made available from a computing device (such as a server) for each grid point covering an indoor environment.